Senior Full Stack Engineer

**Ciklum** is looking for a **Senior Full Stack Engineer** to join our team full\-time in Romania. We are a custom product engineering company that supports both multinational organizations and scaling startups to solve their most complex business challenges. With a global team of over 4,000 highly skilled developers, consultants, analysts and product owners, we engineer technology that redefines industries and shapes the way people live. **About the role:** As a Senior Full Stack Engineer, become a part of a cross\-functional development team engineering experiences of tomorrow. Our client is a 3\-month\-old, seed\-funded ad\-tech startup building infrastructure analytics for publishers. Having successfully launched a POC with design partners, they are now transitioning from a solo\-founder codebase to a founding engineering team of four. The focus is on high\-seniority, autonomous developers who can thrive in a fast\-paced, "startup\-mode" environment without heavy management. * The "Founding Four" Opportunity: You aren't just an employee; you are part of the founding engineering team. You will have a direct hand in shaping the architecture, culture, and product direction from day zero * High\-Impact Engineering: Unlike large corporations where you're a small cog, here you are building the core infrastructure of a platform that processes massive amounts of real\-time data for major publishers * A "No\-Micromanagement" Culture: The CEO is an ad\-tech veteran with multiple exits. He is building a "seniors\-only" team where autonomy is the default and character is as important as code * Modern Tech Stack: Work with Node.js, TypeScript, and AI\-native solutions (LLMs/Agents) without the burden of 10\-year\-old legacy code * Stability \+ Growth: You get the "wild west" excitement of a 3\-month\-old startup but with the security of a seed\-funded company and a founder who has "been there, done that **Responsibilities:** * Design, develop, and maintain scalable full\-stack applications using React, Node.js, and Python * Develop the core product offering implemented to track and analyse billions of events on websites and apps * Develop integrations with Supply\-Side Platforms (SSPs) and Demand\-Side Platforms (DSPs) * Integrate AI/ML capabilities into our platform, including LLM APIs and on\-premise model deployments * Build agentic workflows and AI\-powered automation to enhance platform capabilities * Collaborate with product, data science, and engineering teams to deliver end\-to\-end solutions * Mentor junior developers and contribute to engineering best practices **Requirements:** * 5\+ years of professional software development experience * Strong proficiency in JavaScript/TypeScript, React, and Node.js * Solid experience with Python for backend development and data processing * Experience building high\-performance, low\-latency distributed systems * Strong understanding of RESTful APIs, microservices architecture, and cloud platforms (AWS/GCP) * Experience with databases (SQL and NoSQL) and data streaming technologies * Excellent problem\-solving skills and ability to work autonomously * Strong communication skills and collaborative mindset **What\`s in it for you?** * Strong community: Work alongside top professionals in a friendly, open\-door environment * Growth focus: Take on large\-scale projects with a global impact and expand your expertise * Tailored learning: Boost your skills with internal events (meetups, conferences, workshops), Udemy access, language courses, and company\-paid certifications * Endless opportunities: Explore diverse domains through internal mobility, finding the best fit to gain hands\-on experience with cutting\-edge technologies * Enjoy radical flexibility – work remotely or from an office, your choice * Care: Medical subscription to Regina Maria, meal tickets of 16 ron net/day worked **About us:** At Ciklum, we are always exploring innovations, empowering each other to achieve more, and engineering solutions that matter. With us, you’ll work with cutting\-edge technologies, contribute to impactful projects, and be part of a One Team culture that values collaboration and progress. In Romania, we welcome top\-tier tech talent — whether from our Bucharest office or fully remotely. Tap into deep industry knowledge, grow your career, and make an impact in an empowering environment. Want to learn more about us? Follow us on Instagram, Facebook, . **Explore, empower, engineer with Ciklum!** Interested already? We would love to get to know you! Submit your application. We can’t wait to see you at Ciklum. REQUIRED SKILLS AI Platform JavaScript Node.js React TypeScript JOB INFO Job Identification 2147 Job Category Software Engineering Posting Date 02/25/2026, 05:11 AM Locations RO\-Remote (Remote)